Django 多进程部署下全局变量失效问题解析与解决方案

# my_app/some_module.py
my_global_dict = {} # 初始为空字典的全局变量

# my_app/views.py
from django.shortcuts import render
# 假设 myClass 是一个自定义类
class MyClass:
    def __init__(self):
        self.data = "some_data"

def view1(request):
    """
    此视图向全局字典添加一个MyClass实例。
    """
    my_global_dict["key0"] = MyClass()
    print(f"view1: Global dict after modification: {my_global_dict}")
    return render(request, 'some_template.html', {'message': 'Data added'})

def view2(request):
    """
    此视图尝试访问全局字典。
    """
    print(f"view2: Global dict before access: {my_global_dict}")
    # 期望在此处看到 view1 添加的数据，但实际可能为空字典
    if "key0" in my_global_dict:
        print(f"view2: Retrieved data: {my_global_dict['key0'].data}")
    else:
        print("view2: Global dict is empty or 'key0' not found.")
    return render(request, 'some_other_template.html', {'message': 'Checking data'})

# settings.py

CACHES = {
    "default": {
        "BACKEND": "django.core.cache.backends.memcached.PyMemcacheCache", # 或者 'django.core.cache.backends.memcached.MemcachedCache'
        "LOCATION": "127.0.0.1:11211", # Memcached服务器地址和端口，可以是远程服务器
        "TIMEOUT": 300, # 默认缓存超时时间（秒），这里是5分钟
        "OPTIONS": {
            "MAX_ENTRIES": 1000, # 最大缓存条目数
        }
    }
}

# settings.py

CACHES = {
    "default": {
        "BACKEND": "django.core.cache.backends.redis.RedisCache",
        "LOCATION": "redis://127.0.0.1:6379/1", # Redis服务器地址和端口，/1表示使用数据库1
        "TIMEOUT": 300,
        "OPTIONS": {
            "CLIENT_CLASS": "django_redis.client.DefaultClient",
        }
    }
}

# my_app/views.py
from django.shortcuts import render
from django.core.cache import cache # 导入缓存模块

class MyClass:
    def __init__(self, data="some_data"):
        self.data = data
    def __repr__(self): # 为了方便打印
        return f"MyClass(data='{self.data}')"

def view1(request):
    """
    此视图将MyClass实例存储到缓存中。
    """
    instance = MyClass(data="data_from_view1")
    cache.set("my_shared_key", instance, timeout=300) # 存储到缓存，5分钟过期
    print(f"view1: Stored instance in cache: {instance}")
    return render(request, 'some_template.html', {'message': 'Data added to cache'})

def view2(request):
    """
    此视图从缓存中检索MyClass实例。
    """
    instance = cache.get("my_shared_key") # 从缓存中获取数据
    print(f"view2: Retrieved from cache: {instance}")
    if instance:
        print(f"view2: Retrieved data: {instance.data}")
    else:
        print("view2: Data not found in cache or expired.")
    return render(request, 'some_other_template.html', {'message': 'Checking data from cache'})